Intelligent access point scanning with self-learning capability

ABSTRACT

A method and apparatus for intelligent access point scanning with self-learning capability enables a wireless handset to conserve power while scanning for unlicensed mobile access.

CLAIM OF BENEFIT TO PRIOR APPLICATIONS

This Application is a continuation application of U.S. PatentApplication entitled “Intelligent Access Point Scanning withSelf-Learning Capability,” filed on Aug. 26, 2005, now issued as U.S.Pat. No. 7,515,575, and having Ser. No. 11/212,353. U.S. patentapplication Ser. No. 11/212,353 is incorporated herein by reference.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to commonly owned U.S. application Ser. No.11/013,883, now issued as U.S. Pat. No. 7,640,008, entitled “ApparatusAnd Method For Extending The Coverage Area Of A Licensed WirelessCommunication System Using An Unlicensed Wireless Communication System,”filed Dec. 15, 2004, which is incorporated herein by reference.

TECHNICAL FIELD

This invention relates generally to telecommunications and, moreparticularly, to techniques for accessing unlicensed wirelesscommunication services.

BACKGROUND

Licensed mobile access (LMA) communication systems provide mobilewireless communications over large areas to individuals using wirelesshandsets. Licensed wireless systems include cellular telephone systemsand/or Personal Communication Services (PCS) telephone systems. Wirelesshandsets include cellular telephones, PCS telephones, wireless-enabledpersonal digital assistants, wireless modems, and the like.

Licensed mobile access communication systems utilize public wirelesssignal frequencies that are licensed from a government entity. Licenseespay large fees for access to these frequencies, and make large capitalinvestments in base station and switching equipment which is required tosupport communications over extended geographical areas. As a result,the cost of licensed wireless communication service is generally higherthan voice and data services over wired communication networks such asthe public switched telephone network (PSTN) and private cable systems,which do not pay license fees and which have lower and/or fullyamortized capital costs.

Typically, licensed wireless base stations are installed approximately amile apart from one another and mobile subscribers are handed off fromone base station to another as the subscribers move through the coverageareas (cells) of each base station. The quality of the link between thewireless transceiver and any base station is dependent on factors suchas weather conditions, distance between the base station and thesubscriber, and multipath interference. In contrast, the quality ofwired communication services is not affected by any of theaforementioned factors. As a result, the quality and reliability ofservice (e.g., voice quality, speed of data transfer and bit-error rate)in licensed wireless systems is generally inferior to the quality ofservice afforded by wired connections. Furthermore, in many areas, theavailability of wired communication services is greater than theavailability of licensed wireless communication services. Thus, the userof licensed wireless communication systems pays relatively high fees forlimited availability and relatively low quality service.

As noted above, wired connections are extensively deployed and generallyperform at a lower cost with higher quality voice and higher speed dataservices. The problem with wired connections is that they constrain themobility of a user. To bridge the gap, unlicensed mobile access (UMA)technology has been developed to enable dual-mode (LMA and UMA) wirelesshandsets to access voice and data services provided by core mobilenetwork through unlicensed wireless access points, such as IEEE 802.11(e.g., Wi-Fi) access points or Bluetooth access points, for example.This technology is designed to seamlessly handover a licensed wirelessconnection to an unlicensed wireless connection whenever an unlicensedwireless link to a wired network is available. The unlicensed wirelessconnections operate over limited ranges (e.g., up to 100 meters) andprovide high quality and high reliability links to wired InternetProtocol (IP) access networks.

UMA technology is described in detail in commonly owned copending U.S.Pat. No. 7,640,008, entitled “Apparatus And Method For Extending TheCoverage Area Of A Licensed Wireless Communication System Using AnUnlicensed Wireless Communication System,” filed Dec. 15, 2004 andincorporated herein by reference. In addition, a standard specificationfor UMA technology has been adopted by the European TelecommunicationsStandards Institute (see, ETSI TS 143 318 v6.0.0 2005-01) with respectto GSM and GPRS communication services.

A dual-mode wireless handset is capable of switching automatically andseamlessly between licensed and unlicensed mobile access networks.However, dual-mode operation exacts a cost in battery power, consumed bythe unlicensed radio transceiver to support scanning for unlicensedwireless access points (UWAPs) while the handset is operating incellular voice or data mode. For example, if the unlicensed radio isturned on every 2.5 seconds for access point scanning (a typical defaultscanning rate), the average current drain might be 2.2 milliamperes (ma)for a typical IEEE 802.11 chipset (e.g., the Broadcom BCM4317 bchipset). The average current drain of the cellular radio in standbymode might be 2.5 ma, so the total power consumption of the dual-modehandset could be approximately twice that of a standalone cellularhandset. Decreasing the default scan rate of the unlicensed radio willreduce the power consumption, but decreasing the scan rate too much willintroduce delays (latency) in acquiring and accessing unlicensedwireless access points that are unacceptable to mobile subscribers. TheUMA standard does not specify any mechanism for power management for theunlicensed radio subsystem in a dual-mode handset.

SUMMARY OF EMBODIMENTS OF THE INVENTION

In one embodiment, a method for intelligent access point scanning withself-learning capability includes detecting the identifier of a licensedmobile access cell (LMAC), obtaining a probability measure for accessingan unlicensed mobile access network (UMAN) through an unlicensedwireless access point (UWAP) within the licensed mobile access cell, andscanning for the unlicensed wireless access point with a scan rate thatis determined by the probability measure. In one embodiment, the methodalso includes modifying the probability measure to reflect the resultsof the scan.

In one embodiment, an apparatus includes a wireless interface tocommunicate with a licensed mobile access service and with unlicensedwireless access points. The apparatus also includes a memory to store atable of LMAC identifiers and a processing device coupled with thememory and the wireless interface. The processing device is configuredto detect an LMAC identifier, to obtain a probability measure from thetable for accessing the UMAN through a UWAP within the LMAC, and to scanfor the UWAP with a scan rate that is determined by the probabilitymeasure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a dual-mode system in one embodiment of intelligentaccess point scanning with self-learning capability.

FIG. 2 illustrates a method in one embodiment of intelligent accesspoint scanning with self-learning capability.

FIG. 3 illustrates a dual-mode wireless handset in one embodiment ofintelligent access point scanning with self-learning capability.

FIG. 4A illustrates a data table in one embodiment of intelligent accesspoint scanning with self-learning capability.

FIG. 4B illustrates a lookup table in one embodiment of intelligentaccess point scanning with self-learning capability.

FIG. 4C illustrates scan functions in one embodiment of intelligentaccess point scanning with self-learning capability.

FIG. 5 illustrates another method in one embodiment of intelligentaccess point scanning with self-learning capability.

DETAILED DESCRIPTION

Methods and apparatus for intelligent access point scanning withself-learning capability are described. In the following description,numerous specific details are set forth, such as examples of specificcommands, named components, connections, data structures, etc., in orderto provide a thorough understanding of embodiments of the presentinvention. It will be apparent, however, to one skilled in the art thatembodiments of present invention may be practiced without these specificdetails. In other instances, well known components or methods have notbeen described in detail but rather in a block diagram in order to avoidunnecessarily obscuring the present invention. Thus, the specificdetails set forth are merely exemplary. The specific details may bevaried from and still be contemplated to be within the spirit and scopeof the present invention.

Embodiments of the present invention include circuits and components, tobe described below, which perform operations. Alternatively, theoperations of the present invention may be embodied inmachine-executable instructions, which may be used to cause ageneral-purpose or special-purpose processor programmed with theinstructions to perform the operations. Alternatively, the operationsmaybe performed by a combination of hardware and software.

Embodiments of the present invention may be provided as a computerprogram product, or software, that may include a machine-readable mediumhaving stored thereon instructions, which may be used to program acomputer system (or other electronic devices) to perform a processaccording to the present invention. A machine-readable medium includesany mechanism for storing or transmitting information in a form (e.g.,software, processing application) readable by a machine (e.g., acomputer). The machine-readable medium may include, but is not limitedto: magnetic storage media (e.g., floppy diskette); optical storagemedia (e.g., CD-ROM); magneto-optical storage media; read only memory(ROM); random access memory (RAM); erasable programmable memory (e.g.,EPROM and EEPROM); flash memory; electrical, optical, acoustical orother form of propagated signal; (e.g., carrier waves, infrared signals,digital signals, etc.); or other type of medium suitable for storingelectronic instructions.

Some portions of the description that follow are presented in terms ofalgorithms and symbolic representations of operations on data bits thatmay be stored within a memory and operated on by a processor. Thesealgorithmic descriptions and representations are the means used by thoseskilled in the art to effectively convey their work. An algorithm isgenerally conceived to be a self-consistent sequence of acts leading toa desired result. The acts are those requiring manipulation ofquantities. Usually, though not necessarily, these quantities take theform of electrical or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, parameters, or the like.

The term “coupled to” as used herein may mean coupled directly to orindirectly to through one or more intervening components. Any of thesignals provided over various buses described herein may be timemultiplexed with other signals and provided over one or more commonbuses. Additionally, the interconnection between circuit components orblocks may be shown as buses or as single signal lines. Each of thebuses may alternatively be one or more single signal lines, and each ofthe single signal lines may alternatively be buses.

In the following description, embodiments of the invention may bedescribed in the context of a GSM/GPRS cellular radio system for clarityand simplicity of explanation. One having skill in the art willappreciate that embodiments of the invention may be practiced in thecontext of other licensed wireless communication systems andtechnologies such as, for example, CDMA (code division multiple access),FDMA (frequency division multiple access) and TDMA (time divisionmultiple access) systems using non-GSM protocols.

FIG. 1 illustrates a system 100 in which embodiments of the presentinvention may be practiced. It will be appreciated by those skilled inthe art that other system configurations may also be used to practiceembodiments of the invention. In FIG. 1, a UMA-enabled dual-modewireless handset (handset) 101 is equipped to communicate over alicensed mobile access network (LMAN) 102 operated by a cellular serviceprovider. When the handset is within range of a licensed mobile accesscell (LMAC) 103 of a cellular base transceiver station (BTS) 104, itaccesses the core mobile network 105 of the service provider through aprivate network 106 and a base station controller (BSC) 107 operated bythe service provider, and updates its location with the core mobilenetwork 105.

The handset 101 is also equipped to communicate over an unlicensedmobile access network (UMAN) 108 with unlicensed wireless access points(UWAPs) (e.g., Wi-Fi and Bluetooth access points) such UWAP 109 withaccess to the core mobile network 105 through a broadband IP network110. The UMAN includes a UMA network controller (UNC) 111, operated bythe service provider, which routes voice and data communications to thecore mobile network 105.

When the handset 101 is connected to the licensed mobile access network102, it scans for unlicensed wireless access points to which the handsetis allowed to connect (e.g., unencrypted public or private access pointsor encrypted access points for which the wireless handset has a passphrase, such as a WEP pass phrase in an IEEE 802.11 wireless network) ina manner described in detail below. When the handset 101 moves withinrange of such an unlicensed wireless access point, and detects theaccess point, the handset negotiates a connection.

Upon connecting, the handset registers with the UMA Network Controller111 over the broadband IP network 110, to be authenticated andauthorized to access voice and data services over the broadband IPnetwork 110 via the unlicensed wireless connection 112. Upon UMAregistration, the handset may optionally decide to update its locationwith core mobile network 105, and from that point on all mobile voiceand data traffic is routed to the handset 101 via the UMAN 108 ratherthan the LMAN 102.

In one embodiment, dual-mode wireless handset 101 may be equipped with atransceiver for a licensed wireless communication service (e.g.,GSM/GPRS, CDMA, FDMA and the like) that provides licensed mobile access(LMA) to the core mobile network 105 of the licensed wirelesscommunication service through licensed mobile access network (LMAN) 102.Handset 101 may also be equipped with a transceiver for an unlicensedwireless connection (e.g., IEEE 802.11 and/or Bluetooth) that providesunlicensed mobile access (UMA) to the core mobile network 105 of thelicensed wireless communication service via unlicensed wireless accesspoints such as UWAP 109 and wired IP access networks such as IP accessnetwork 110.

In LMA mode, when the handset comes within range of a licensed mobileaccess cell (LMAC), it identifies its current location by an identifierof the LMAC. In one embodiment, each LMAC may be identified by alocation area identifier (LAI), which is common to a group of LMACs, andby a cell identifier (CI) within the LAI. Together, the LAI and the CImay make up a global cell identifier (GCI) that uniquely identifies eachLMAC.

In one embodiment, when the handset is in LMA mode and within range ofan LMAC, it detects the identifier of the LMAC and compares theidentifier with a table of LMAC identifiers to determine whether thehandset has previously been within range of the LMAC and whether thehandset has successfully accessed a UWAP within range of the LMAC. Ifthe data in the table contains a record of the LMAC, the handset obtainsa parameter from the table that is indicative of the likelihood ofsuccessfully accessing a UWAP within the LMAC.

As described in greater detail below, the parameter may represent a“credit score” or probability measure for accessing a UWAP within theLMAC, based on prior experience within the LMAC. The parameter may thenbe used to enter a lookup table that specifies a scan rate that theunlicensed transceiver will use to search for a UWAP. The higher theparameter value, the greater the probability of finding a UWAP withinthe LMAC that can successfully register the wireless handset with theUMAN.

Each time a search for a UWAP within a particular LMAC is successful,and a connection to the UMAN is established, the credit score for thatLMAC may be increased, resulting in an increased scan rate the next timethe wireless handset roams onto that LMAC. Conversely, if the search fora UWAP is unsuccessful, or the wireless handset is unable to connect tothe UMAN through a UWAP, the credit score for that LMAC may bedecreased, resulting in a decreased scan rate the next time the wirelesshandset roams onto that LMAC.

FIG. 2 illustrates one embodiment 200 of this method. In step 201, thehandset detects the identifier of a licensed mobile access cell. In step202, the handset obtains the probability measure associated with thelicensed mobile access cell for accessing an unlicensed wireless accesspoint to the unlicensed mobile access network. In step 203, the handsetscans for an unlicensed wireless access point to the unlicensed wirelessaccess network with a scan rate determined by the probability measure.

FIG. 3 illustrates a dual-mode wireless handset 300 in one embodiment ofintelligent access point scanning with self-learning capability.Wireless handset 300 includes a processing device 301 which may be ageneral-purpose processor (e.g., a microprocessor), special purposeprocessor such as a digital signal processor (DSP) or other type ofdevice such as a controller or field programmable gate array (FPGA).Processing device 301 may be coupled with a wireless interface 302,which may include a licensed mobile access transceiver 303 (e.g., a GSMor CDMA transceiver or the like) adapted to communicate wirelessly witha licensed mobile access network, and an unlicensed mobile accesstransceiver 304 (e.g., an IEEE 802.11 or Bluetooth transceiver or thelike) adapted to communicate with an unlicensed mobile access network.

Processing device 301 may also be coupled with a memory 305, which maybe any combination of volatile and/or non-volatile memory capable ofstoring data and/or instructions. Memory 305 may include an area ofmemory configured as a data table 306 to hold information relating tolicensed mobile access cells as described in greater detail below.Memory 305 may also include an area of memory configured as a lookuptable 307, which may be used to associate the credit scores (i.e.,probability measures) of each LMAC in data table 306 with a UWAP scanrate. Handset 300 may also include a user interface 308 coupled with theprocessing device 301 to enable voice and data input and output for auser of the wireless handset 300.

FIG. 4A illustrates an exemplary logical structure of data table 306.Physical structures of data tables in memory are known in the art and,accordingly, are not described in detail. Data table 306 may include alist 401 of n LMAC identifiers LMAC(i) (e.g., LMAC(1), LMAC (2), . . . ,LMAC (n)), which may be global cell identifiers, for example. The LMACidentifiers may consist of two parts: a first part common to a localgroup of LMACs, denoting an LMA service area (e.g., a local areaidentifier, LAI(i) for example), and a second part that identifies aparticular LMAC within the local group of LMACS (e.g., a cellidentifier, CI(i) for example).

Data table 306 may also contain a list 402 of n credit scores CS(i)(e.g., CS(1), CS(2), . . . , CS(n)) corresponding to the list 401 ofLMAC identifiers LMAC(i), where each credit score in the list denotes aprobability measure for successfully connecting with a UMAN through aUWAP in the corresponding LMAC. Data table 306 may also contain a list403 of timestamps T(i) (e.g., T(1), T(2), . . . , T(n)), one for eachLMAC identifier in the list 401 of LMAC identifiers, denoting the latest(i.e., most recent) time that the wireless handset has made a successfulUMA connection to the UMAN through a UWAP in the corresponding LMAC.Each timestamp T(i) may include both time and date information.Timestamps T(i) may be derived from an internal clock (not shown) inhandset 300. Alternatively, timestamps T(i) may be derived from systemclocks in LMAN 102 and/or UMAN 108 as are known in the art.

FIG. 4B illustrates an exemplary logical structure of lookup table 307.Physical structures of lookup tables in memory are known in the art and,accordingly, are not described in detail. Lookup table 307 may have anentry column 404 and an output column 405. The entry column of lookuptable 307 may be a list of credit scores ranging from zero to a maximumvalue m, and the output column of lookup table 307 may be a list of scanrates ranging from a minimum scan rate corresponding to a credit scoreof zero, to a maximum scan rate corresponding to the maximum creditscore m. In one embodiment, the minimum scan rate corresponding to acredit score of zero may be a zero scan rate (i.e., no scan).

Lookup table 307 may define any arbitrary functional relationshipbetween credit scores and scan rates. For example, there may be a linearrelationship as illustrated by curve 406 in FIG. 4C, or a nonlinearrelationship as illustrated by curve 407 in FIG. 4C. It will beappreciated that while curves 406 and 407 are illustrated as continuouscurves, the actual values of scan rates may be discrete valuescorresponding to discrete values of credit scores in lookup table 307.

FIG. 5 is a flowchart illustrating a method in one embodiment ofintelligent access point scanning with self-learning capability. Themethod begins when handset 300 scans for an LMAC such as LMAC 103 (step501). If an LMAC is not detected at step 502, the handset 300 scans fora UWAP at a default rate (step 503). If a UWAP is not detected within aspecified time period ΔT (e.g., 10 minutes) at step 504, the handset 300continues to scan at the default scan rate (step 505) and checks whethera new LMAC has been detected (step 506).

If a new LMAC is not detected at step 506, the method continues loopingthrough steps 504 and 505 until a new LMAC is detected at step 506. If anew LMAC is detected at step 506, the method continues at step 507 wherepath loss parameters for the detected LMAC are evaluated (e.g., todetermine link quality). If the path loss parameters are below aspecified threshold, the method reverts to the “no LMAC detected” modeat step 503. If the path loss is OK at step 507, the handset 300compares the identifier of the detected LMAC to the list 401 of LMACidentifiers (monitored cell list) in data table 306 (step 508). At step509, if the identifier of the (detected) LMAC matches both the LAI andthe CI of an LMAC identifier in the list 401 of LMAC identifiers in datatable 306, the handset 300 scans for a UWAP at a scan rate correspondingto the credit score in the list 402 of credit scores that is associatedwith the detected LMAC (step 510).

The scan rate is determined by locating the credit score of the detectedLMAC in the list 404 of credit scores in lookup table 307 to acorresponding scan rate in the list of scan rates 405 in lookup table307. If a UWAP is located within the specified time ΔT at step 511, thehandset 300 attempts to register with the UMAN 102 at step 512. If theregistration is successful at step 512, the handset 300 compares thecurrent time (from local or network clocks as described above) with thetimestamp in the list of timestamps 403 associated with the detectedLMAC (step 513). If the registration with the UMAN 102 is the firstregistration in the last M hours (e.g., 12 hours), then the credit scorefor the detected LMAC is incremented by one count (step 514). Next, thetimestamp is updated to the current time at step 515. If, at step 513,the registration with the UMAN 102 is not the first registration in thelast M hours, the credit score for the detected LMAC is not incrementedand the timestamp is updated to the current time at step 515.

Returning to step 511, if a UWAP is not located within the specifiedtime ΔT, or, if at step 512, the handset 300 does not registersuccessfully with UMAN 102, handset 300 scans for a UWAP at the defaultrate (step 515). If the detected LMAC identifier does not change at step516, the method continues at step 511. If the detected LMAC at step 516changes, the method continues at step 507 as previously described.

If, at step 509, the identifier of the detected LMAC matches only theLAI of an LMAC identifier in the list 401 of LMAC identifiers in datatable 306 (e.g., there is an LAI match without a CI match), the methodassigns a credit score of 1 to the identified LMAC and the handset 300scans for a UWAP at a scan rate corresponding to a credit score of 1 inlookup table 307 (step 517). The method continues with a return to step504, where, if a UWAP is not located within the time ΔT, the methodcontinues at step 505 as previously described. If, at step 504, a UWAPis located within the time ΔT, and UMA registration is successful atstep 518, the currently detected LMAC is added to the monitored celllist (list 401) with a credit score of 2 at step 519, and the timestampassociated with the detected LMAC is updated to the current time at step515. If, at step 518, the registration with the UMAN is not successful,scanning for a UWAP continues at the default rate at step 505.

If, at step 509, the identifier of the currently detected LMAC does notmatch all or a portion of an LMAC identifier in the monitored cell list401, the currently detected LMAC is entered in the list with a creditscore of 0 and scanning for a UWAP is suspended (step 520). At step 521,an unprompted manual override option may be invoked by the user ofhandset 300. If the user invokes a manual override at step 521, themethod continues to scan at the default scan rate at step 503.Otherwise, the method scans for an LMAC at step 501.

The method 500 may also include an audit of the monitored cell list(step 522). In step 522, each timestamp in the list of timestamps 403 ofeach LMAC identifier in the list 401 of LMAC identifiers is examined todetermine if the timestamp is older than a specified period of time(e.g., M hours) compared to the current time. If the timestamp is olderthan the specified period of time, then the credit score for thecorresponding LMAC identifier is decremented by one count. If thedecremented count reduces the credit score of an LMAC identifier in thetable of LMAC identifiers to a specified minimum value, then the LMACidentifier is deleted from the table of LMAC identifiers.

Step 521 may also include a limit on the number of LMAC identifiers inthe table of LMAC identifiers. In step 521, if the table of LMACidentifiers includes the maximum number of LMAC identifiers n, step 521may delete the LMAC identifier with the least credit score (probabilitymeasure) and, if two or more LMAC identifiers have the same creditscore, then the LMAC identifier with the oldest timestamp may bedeleted.

Thus, embodiments of intelligent access point scanning withself-learning capability have been described. While some specificembodiments of the invention have been shown, the invention is not to belimited to these embodiments. The invention is to be understood aslimited only by scope of the appended claims.

1. A method for reducing power consumption of a wireless handset in acommunication system comprising (1) a licensed first wirelesscommunication system comprising a set of access cells and (2) a secondwireless communication system comprising a set of wireless access pointsand a network controller for communicatively coupling the wirelesshandset to the licensed first wireless communication system through awireless access point, the method comprising: detecting an identifierassociated with an access cell of the licensed first wirelesscommunication system; and setting a scan rate for connecting to thelicensed first wireless communication system through a wireless accesspoint of the second wireless communication system based upon priorexperience of detecting wireless access points of the second wirelesscommunication system within the access cell associated with saididentifier.
 2. The method of claim 1 further comprising assigning aprobability measure to the detected identifier to reflect a result ofscanning for the wireless access point of the second wirelesscommunication system within the access cell of the licensed firstwireless communication system associated with the identifier, whereinthe probability measure determines the scan rate.
 3. The method of claim2 further comprising creating a monitored list of identifiers andassigning each identifier a corresponding probability measure in themonitored list, wherein each identifier is associated with a particularaccess cell of the licensed first wireless communication system.
 4. Themethod of claim 3, wherein the scan rate is set to a default scan ratewhen a particular identifier matches an identifier in the monitored listbut fails to connect to a wireless access point within the access cellassociated with the identifier.
 5. The method of claim 3 furthercomprising reducing the probability measure for a particular identifierin the monitored list when attempts to access a wireless access point isunsuccessful within the access cell associated with the particularidentifier.
 6. The method of claim 3 further comprising increasing theprobability measure for a particular identifier in the monitored listwhen a connection to the licensed first wireless communication system issuccessful through a wireless access point within the access cellassociated with the particular identifier.
 7. The method of claim 3further comprising setting the probability measure to a zero scan ratewhen the detected identifier does not match an identifier in themonitored list.
 8. The method of claim 3 further comprising scanning ata default rate when a user overrides the scan rate determined by themonitored list of identifiers.
 9. The method of claim 3 furthercomprising setting the probability measure to a default scan rate whichcorresponds to a non-zero scan rate when the detected identifier is apartial match to an identifier in the monitored list.
 10. Thenon-transitory computer readable medium of claim 1, wherein the computerprogram further comprises a set of instructions for assigning aprobability measure to the detected identifier to reflect a result ofscanning for the wireless access point of the second wirelesscommunication system within the access cell of the licensed firstwireless communication system associated with the identifier, whereinthe probability measure determines the scan rate.
 11. The non-transitorycomputer readable medium of claim 10, wherein the computer programfurther comprises a set of instructions for creating a monitored list ofidentifiers and assigning each identifier a corresponding probabilitymeasure in the monitored list, wherein each identifier is associatedwith a particular access cell of the first licensed first wirelesscommunication system.
 12. A computer-readable medium storing a computerprogram, wherein the computer-readable medium is a physical storagemedium and not propagated signals, the computer program for reducingpower consumption of a wireless handset in a communication systemcomprising a licensed first wireless communication system comprising aset of access cells, and a second wireless communication systemcomprising a set of wireless access points and a network controller forcommunicatively coupling the wireless handset to the licensed firstwireless communication system, the computer program comprising sets ofinstructions for: storing a list of access cell identifiers of thelicensed first wireless communication system, wherein each particularaccess cell identifier has an associated probability measure forconnecting the wireless handset to the first wireless communicationsystem through a wireless access point of the second wirelesscommunication system; updating the list each time an access cellidentifier is detected; and setting a scan rate for accessing a wirelessaccess point of the second wireless communication system based on theprobability measure associated with a detected access cell identifier inthe list.
 13. The computer-readable medium of claim 12, wherein the setof instructions for updating the list comprises a set of instructionsfor increasing the probability measure associated with a particularaccess cell identifier when the wireless handset successfully connectsto the first wireless communication system through a wireless accesspoint of the second wireless communication system within an access cellassociated with the particular access cell identifier.
 14. Thecomputer-readable medium of claim 12, wherein the set of instructionsfor updating the list comprises a set of instructions for decreasing theprobability measure associated with a particular access cell identifierwhen the wireless handset does not connect to the first wirelesscommunication system through a wireless access point of the secondwireless communication system within an access cell associated with theparticular access cell identifier.
 15. The computer-readable medium ofclaim 12, wherein the computer program further comprises a set ofinstructions for auditing the list of access cell identifiers, whereinauditing the list of access cell identifiers removes access cellidentifiers in the list that have a corresponding minimum probabilitymeasure.
 16. The computer-readable medium of claim 12, wherein thecomputer program further comprises a set of instructions for storing atimestamp for each access cell identifier, the timestamp of eachparticular access cell identifier corresponding to a last time asuccessful registration with the licensed first wireless communicationsystem occurs through a wireless access point of the second wirelesscommunication system within an access cell associated with theparticular access cell identifier.
 17. The computer-readable medium ofclaim 16 further comprising a set of instructions for auditing the listof access cell identifiers, wherein auditing the list of access cellidentifiers removes access cell identifiers with an oldest timestamp.18. A wireless handset, comprising: a wireless interface to communicatewith (1) a licensed first wireless communication system comprising a setof access cells and (2) a second wireless communication systemcomprising a set of wireless access points and a network controller forcommunicatively coupling the wireless handset to the licensed firstwireless communication system; a memory for storing a list ofidentifiers, wherein each identifier is associated with an access cellof the licensed first wireless communication system; and a processorcoupled to the memory and the wireless interface, the processor for:detecting an identifier associated with an access cell of the licensedfirst wireless communication system; obtaining a probability measureassociated with the detected identifier from the list; and setting ascan rate determined by the probability measure for accessing a wirelessaccess point of the second wireless communication system that resideswithin the identified access cell of the licensed first wirelesscommunication system.
 19. The wireless handset of claim 18, wherein theprobability measure reflects a probability of connecting to a particularwireless access point in the set of wireless access points within aparticular access cell in the set of access cells.
 20. The wirelesshandset of claim 18, wherein the processor is further for modifying theprobability measure associated with a particular identifier based onwhether a connection to a particular wireless access point isestablished within the access cell associated with the particularidentifier.
 21. The wireless handset of claim 18, wherein the processoris further for updating the probability measure associated with aparticular identifier in the list of identifiers after at least oneattempt to connect to a wireless access point within the access cellassociated with the particular identifier.
 22. A non-transitory computerreadable medium storing a computer program for reducing powerconsumption of a wireless handset in a communication system comprising alicensed first wireless communication system comprising a set of accesscells and a second wireless communication system comprising a set ofwireless access points and a network controller for communicativelycoupling the wireless handset to the licensed first wirelesscommunication system through a wireless access point, the computerprogram comprising sets of instructions for: detecting an identifierassociated with an access cell of the licensed first wirelesscommunication system; and setting a scan rate for connecting to thelicensed first wireless communication system through a wireless accesspoint of the second wireless communication system based upon priorexperience of detecting wireless access points of the second wirelesscommunication system within the access cell associated with saididentifier.